"The nanotechnology industry welcomed the findings but cautioned against drawing conclusions from a single study", Dr Steffi Friedrichs, Director of the Nanotechnology Industries Association (NIA) told BBC News. "Until now we have not had two studies that showed the same result", she adds.

In an interview with Chemistry World Dr Friedrichs adds: "It is not surprising that long insoluble fibres of any material should behave in this way - glass wool has similar effects...but the study needs to be verified, and the researchers have noted important caveats - for example whether nanotubes can actually get to the place in the body that's going to cause damage".

The authors of the study support the industries’ safety claims: "Even if you took a mallet and hammered a tennis racket [containing carbon nanotubes], there's probably no danger because the nanotubes are held in a polymer matrix", says Professor Ken Donaldson.